No abstract

The dielectric properties of low-density polyethylene-chitosan composite films were correlated with their antibacterial properties in this work. Films were designed on the molecular level using palm oil as a plasticizer in an internal mixer. Maleic anhydride and dicumyl peroxide were used as a coupling agent and a free radical initiator, respectively. The dielectric properties of the composite films were studied as a function of chitosan loading, presence of plasticizer and variable applied frequency. The dielectric constant of the samples was positively correlated with the amount of chitosan in the polythene matrix. The antibacterial properties of the composite films were also studied. A distinct inhibitory zone against Escherichia coli and Staphylococcus aureus developed, and this zone increased in diameter with chitosan loading. The low-molecular-weight chitosan-based polyethylene films showed significant improvement in dielectric and antibacterial properties when compared with the native chitosan-based films. These studies show that the antibacterial properties of the developed films were complementary with their dielectric properties. This study suggests the possibility of using the dielectric properties of composites as a measure of their antibacterial properties.

Composite membranes based on ethylene propylene diene monomer (EPDM) and polyvinyl chloride (PVC) has been prepared. The vapor permeation studies were conducted with aromatic hydrocarbons and aliphatic alcohols for the membrane characterization. Special attention has been given to the amount of PVC in the membrane, size of penetrant and also type of vulcanization. The permeability was found to decrease with increase in PVC content due to the stiff and rigid nature of PVC. The field emission scanning electron microscopy of the membranes showed a two-phase morphology. Here, the PVC is dispersed in the continuous EPDM phase. It was found that the permeability decreased with increase in the size of the penetrant. Different types of miscible liquid mixtures have been analyzed for finding out the separation efficiency of the membranes. In the case of benzene/propanol mixture, it has been found that when the concentration of benzene increases, the vapor permeation rate increases, indicating high interaction of benzene toward the composites.

A systematic study based on the size reduction of chitosan particles has been conducted by de-acetylation by using various concentrations of NaOH solutions at different reaction temperature and time. The degree of de-acetylation (DD) of the isolated chitosan particles has been correlated with their molecular weight and ash content. It was found that degree of de-acetylation of the samples increased with increase in concentration of alkali and reaction temperature. The scanning electron micrographs showed that the particle size of chitosan decreases with a reduction in molecular weight. The observed size of particles with lowest molecular weight was in the range of 200–450 nm. The crystallinity and thermal stability of the particles were studied by using XRD and TGA respectively. The results showed that crystalline properties of the de-acetylated chitosan particles were increased with increase in concentration of NaOH and degree of de-acetylation. The particles prepared at 170°C have been found maximum thermal stability. The antimicrobial activity of the chitosan particles has been also studied with Escherichia coli, and the inhibitory zone diameters against the bacteria were found to increase with the degree of de-acetylation.